Re: [Shutup] [ietf-smtp] Levels of proposals

Chris Lewis <ietf@mustelids.ca> Fri, 04 December 2015 22:19 UTC

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From: Chris Lewis <ietf@mustelids.ca>
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Subject: Re: [Shutup] [ietf-smtp] Levels of proposals
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On 12/04/2015 02:18 PM, Ned Freed wrote:

> We're also getting reports of activities that look like attempts to trick
> MTAs into relay through the use of oddball address formats, some legal,
> some not. Not sure if this is what you're seeing or not.

What you're describing sounds like old-school open relay trickery. 
Indeed, what you could be seeing is decade or older open relay testers 
being used to scan for "buggy" open relay prevention.

What I'm seeing isn't that at all.  What I see is more like "for 
everybody I want to spam (address A), pick another address (address B), 
connect to address B's MX, forge the email to be From: address B, and 
attempt to get B's MX to relay to address A".

However, it's possible that what I'm seeing would shift gears to more 
obvious trickery if the first attempt failed.  It you see the same IP 
hitting more normal relay rejects before trying the oddball addresses, 
it could be.

If you sent me a log record or received string[s] (off-forum please) I 
can probably tell for sure.